13COMP CAT

network communication protocols

13COMP

CAT external

CAT external exemplars

assessment

complexity and tractability

computer vision

big data

computer graphics

formal languages

Level 3 CAT

13COMP & 13DTEC

Date: Friday 23rd October

Time: 1pm to 4pm

DURATION: 3hrs to complete 91908 (COMP) &/or 91909(DTEC)

ROOM: Students will be allocated a room to go to sit the exam (not necessarily with their class).

What exactly is 'network communication protocols'?

My notes on answering the CAT exam

Contains a number of links to useful sites.

13COMP Network Protocols

Companion form to my notes on the CAT

Fill out your copy of this doc which is attached to the

CAT External: list your topics/sub topics Google Classroom assignment.

13COMP 3.9 CAT: list your topics/sub topics

NCEA guide for the old standard AS91636 (3.44)

A good place to start

What is the internet

wires, cables & wifi - more of interest

IP addresses & DNS

Packets, routing & reliability

HTTP & HTML

6 networking tutorials from scratch

INTRODUCTION TO NETWORKS

Networks connect devices, devices share information

To share information, they must speak the same language - this language is called a protocol.

Network types: SOHO network, enterprise network, LAN, WAN

THIS VIDEO IS NOT ON NETWORK PROTOCOLS, but you may find it interesting.

Detail on copper & fibre cabling

Mentions that Ethernet protocol is specified by Institute of Electrical and Electronics Engineers (IEEE). Ethernet standard is: IEEE_802.3

Network protocols - several need to interact to send data over a network.

How they interact can be complicated and that is why we have Network models:.

This video is on the OSI model - owned by the International Standards Organisation (ISO)

YOU DON'T NEED TO GO INTO THE OSI MODEL, but it gives you an insight into how sending data over the network involves multiple network protocols.

THIS VIDEO IS NOT ON NETWORK PROTOCOLS, but you may find it interesting.

IP addressing: describes IPV4

1981 saw the introduction of classful networking - IP address split onto classes

1993 saw the introduction of subletting and CIDR notation.

THIS VIDEO IS NOT ON NETWORK PROTOCOLS, but you may find it interesting.

VLSM - Variable Length Subnet Masks

unicast, broadcast & multicast.

IP addresses are assigned by the Internet Assigned Numbers Authority (IANA).

Static, dynamic IP Addresses and IPAPA addressing.

WORTH WHILE WATCHING

TCP/IP model - in competition to the OSI model.

Developed by the US Department of Defense. and become the most popular network model. Actively took into account existing protocols.

This model is in competition to the OSI model.

Covers http and therefore TCP and IP protocls.

Looking at specific protocols

Who manages the protocols?

The Internet Engineering Task Force (IETF) is an open standards organization, which develops and promotes voluntary Internet standards, in particular the standards that comprise the Internet protocol suite (TCP/IP).
The International Standards Organisation (OSI) is a multinational organization that tries to standardize network communication protocols at the international level. OSI (Open System Interconnection) is a model that ISO put together as a networking communication standard.
The Internet Consortium for Assigned Names and Numbers (ICANN) controls the DNS hierarchy and the allocation of IP addresses

OSI and TCP/IP Layers & associated protocols

TCP/IP

A simple overview

TCP/IP

A bit more in depth

UDP vs TCP

The 5 layer network model is the TCP/IP model.

Goes into detail with UDP and TCP protocols.

HTTP, HTTPS & SSL

FTP

POP3 vs IMAP

The Future and Protocols

From: APNIC - Internet protocols are changing

Background

When the Internet started to become widely used in the 1990s, most traffic used just a few protocols: IPv4 routed packets, TCP turned those packets into connections, SSL (later TLS) encrypted those connections, DNS named hosts to connect to, and HTTP was often the application protocol using it all.

For many years, there were negligible changes to these core Internet protocols.

As a result, network operators, vendors, and policymakers that want to improve (and sometimes, control) the Internet have adopted a number of practices based upon the official protocol to tweak things, whether intended to debug issues, improve quality of service, or impose policy.

Now, significant changes to the core Internet protocols are underway. While they are intended to be compatible with the Internet at large (since they won’t get adoption otherwise), they might be disruptive to those who have taken liberties with undocumented aspects of protocols or made an assumption that things won’t change.

Why we need to change the Internet

There are a number of factors driving these changes.

The limits of the core Internet protocols have become apparent, especially regarding performance. Because of structural problems in the application and transport protocols, the network was not being used as efficiently as it could be, leading to end-user perceived performance (in particular, latency).

This translates into a strong motivation to evolve or replace those protocols because there is a large body of experience showing the impact of even small performance gains.

The ability to evolve Internet protocols — at any layer — has become more difficult over time, largely thanks to the unintended uses by networks discussed above. For example, HTTP proxies that tried to compress responses made it more difficult to deploy new compression techniques; TCP optimization in middleboxes made it more difficult to deploy improvements to TCP.

Finally, we are in the midst of a shift towards more use of encryption on the Internet. Encryption is one of best tools we have to ensure that protocols can evolve and many protocols have been developed to insist on encryption.

You can read about these further by going to the APNIC site referenced above.

Determining the best network path

from CISCO

Determining the best path involves the evaluation of multiple paths to the same destination network and selecting the optimum or shortest path to reach that network. Whenever multiple paths to the same network exist, each path uses a different exit interface on the router to reach that network.

The best path is selected by a routing protocol based on the value or metric it uses to determine the distance to reach a network. A metric is the quantitative value used to measure the distance to a given network. The best path to a network is the path with the lowest metric.

Dynamic routing protocols typically use their own rules and metrics to build and update routing tables. The routing algorithm generates a value, or a metric, for each path through the network. Metrics can be based on either a single characteristic or several characteristics of a path. Some routing protocols can base route selection on multiple metrics, combining them into a single metric.

The following lists some dynamic protocols and the metrics they use:

Routing Information Protocol (RIP): Hop count
Open Shortest Path First (OSPF): Cisco routers use a cost based on cumulative bandwidth from source to destination
Enhanced Interior Gateway Routing Protocol (EIGRP): Bandwidth, delay, load, reliability

in case you thought networks were networks...

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